Bullich, E.; Díaz-González, F.; Aragüés, M.; Girbau-Llistuella, F.; Olivella, P.; Sumper, A. Applied energy Vol. 212, p. 340-361 DOI: 10.1016/j.apenergy.2017.12.048 Data de publicació: 2018-02-15 Article en revista
Microgrids are considered one of the most promising solutions to integrate renewable distributed generation into the electric power system. During the last decade, the microgrid concept has been studied and developed and nowadays it is becoming a reality. Hence, in the coming years a transformation of the current electric power system to a multi-microgrid power system can be expected. In this direction, the study of multi-microgrids is currently being explored. Accordingly, this paper examines the possible multi-microgrid architectures to form a grid of microgrids. For this purpose, the microgrid as a single entity and its possible interactions with external grids is first defined. Then, the possible multi-microgrid architectures are defined in terms of layout, line technology and interface technology. Finally, a comparison between the different architectures is performed in terms of cost, scalability, protection, reliability, stability, communications and business models. This analysis is expected to be of great utility for grid planners and policy makers, who can select the most adequate architecture in function of their necessities.
Olivella, P.; Bullich, E.; Aragüés, M.; Sumper, A.; Ottesen, S.; Vidal, J.; R. Villafafila-Robles Applied energy Vol. 210, p. 881-895 DOI: 10.1016/j.apenergy.2017.08.136 Data de publicació: 2018-01-15 Article en revista
The increasing penetration of distributed energy resources in the distribution grid is producing an ever-heightening interest in the use of the flexibility on offer by said distributed resources as an enhancement for the distribution grid operator. This paper proposes an optimization problem which enables satisfaction of distribution system operator requests on flexibility. This is a decision-making problem for a new aggregator type called Smart Energy Service Provider (SESP) to schedule flexible energy resources. This aggregator operates a local electricity market with high penetration of distributed energy resources. The optimization operation problem of SESP is formulated as an MILP problem and its performance has been tested by means of the simulation of test cases in a local market. The novel problem has also been validated in a microgrid laboratory with emulated loads and generation units. The performed tests produced positive results and proved the effectiveness of the proposed solution.
Ensuring resilient operation and control of smart grids is fundamental for empowering their deployment, but challenging at the same time. Accordingly, this study proposes a novel methodology for evaluating resilience of Information and Communication Technology (ICT) systems for smart distribution grids. Analysing how the system behaves under changing operating conditions a power system perspective allows to understand how resilient the smart distribution grid is, but the resilience of the ICT system in charge of its operation affects the overall performance of the system and does, therefore, condition its resilience. With the aim of systematising the evaluation of ICT systems’ resilience, this study proposes to combine a standardized modelling of Smart Grids, the Smart Grid Architecture Model (SGAM), with a data structured diagram, the Entity Relationship Model (ERM). The architecture of smart distribution grids is analysed through SGAM. Then, their technical characteristics and functionalities are defined and represented in a ERM diagram. Finally, the attributes or properties of the system components are used to formulate resilience indicators against different types of disturbances. This methodology is then applied to analyse the resilience of a ICT platform being developed in EMPOWER H2020 project.
An inspiration for INVADE are the world-wide agreements on minimisation of human caused effects to climate change and energy efficiency targets set at the European Union with ambitious goals for reduction of greenhouse gas emission and for increase of renewable energy share.
To enable a higher share of renewable energy sources to the smart grid and gain a traction in the market place a few critical barriers must be overcome. There is a deficiency of 1) flexibility and battery management systems 2) exploration of ICT solutions based on active end user participation 3) efficient integration of energy storage and transport sector (EVs), 4) novel business models supporting an increasing number of different actors in the grid.
INVADE addresses these challenges by proposing to deliver a Cloud based flexibility management system integrated with EVs and batteries empowering energy storage at mobile, distributed and centralised levels to increase renewables share in the smart distribution grid. The project integrates different components: flexibility management system, energy storage technologies, electric vehicles and novel business models. It underpins these components with advanced ICT cloud based technologies to deliver the INVADE platform. The project will integrate the platform with existing infrastructure and systems at pilot sites in Bulgaria, Germany, Spain, Norway and the Netherlands and validate it through mobile, distributed and centralised use cases in the distribution grid in large scale demonstrations. Novel business models and extensive exploitation activities will be able to tread the fine line between maximizing profits for a full chain of stakeholders and optimizing social welfare while contributing to the standardization and regulation policies for the European energy market. A meaningful integration of the transport sector is represented by Norway and the Netherlands pilots – with the highest penetration of EVs worldwide.
The purpose of this paper is to describe the roles, services and relationships that a local market would encompass, and the type of market interactions that should take place in it. The local market place constitutes an arena for a new business role - the smart energy service provider, which represents the entity with the most central functionalities with respect to local market operation. The local market is described as consisting of three key elements of brokerage/sale: energy, flexibility and other services. Three alternative market settings are considered: islanding mode, interaction with the wholesale market and a third one where other market agents (aggregators/retailers) carry the interactions with the wholesale market. Finally, the paper specifies the relationship between the smart energy service provider and the various local market actors and provides a clarifying user case.
Olivella, P.; Viñals, G.; Sumper, A.; R. Villafafila-Robles; Bremdal, B.; Ilieva, I.; Ottesen, S. IEEE International Energy Conference and Exhibition p. 1-6 Data de presentació: 2016-04-07 Presentació treball a congrés
Eduardo Prieto-Araujo; Olivella, P.; Cheah-Mane, M.; R. Villafafila-Robles; Gomis-Bellmunt, O. Renewable and sustainable energy reviews Vol. 50, p. 325-345 DOI: 10.1016/j.rser.2015.04.101 Data de publicació: 2015-10-01 Article en revista
This paper reviews the renewable energy systems emulators proposals for microgrid laboratory testing platforms. Four emulation conceptual levels are identified based on the literature analysis performed. Each of these levels is explained through a microgrid example, detailing its features and possibilities. Finally, an experimental microgrid, built based on emulators, is presented to exemplify the system performance. (C) 2015 Elsevier Ltd. All rights reserved.
Electric Vehicles (EVs) have seen significant growth in sales recently and it is not clear how power systems will support the charging of a great number of vehicles. This paper proposes a methodology which allows the aggregated EV charging demand to be determined. The methodology applied to obtain the model is based on an agent-based approach to calculate the EV charging demand in a certain area. This model simulates each EV driver to consider its EV model characteristics, mobility needs, and charging processes required to reach its destination. This methodology also permits to consider social and economic variables. Furthermore, the model is stochastic, in order to consider the random pattern of some variables. The model is applied to Barcelona’s (Spain) mobility pattern and uses the 37-node IEEE test feeder adapted to common distribution grid characteristics from Barcelona. The corresponding grid impact is analyzed in terms of voltage drop and four charging strategies are compared. The case study indicates that the variability in scenarios without control is relevant, but not in scenarios with control. Moreover, the voltages do not reach the minimum voltage allowed, but the MV/LV substations could exceed their capacities. Finally, it is determined that all EVs can charge during the valley without any
negative effect on the distribution grid. In conclusion, it is determined that the methodology presented allows the EV charging demand to be calculated, considering different variables, to obtain better accuracy in the results.
This article investigates the combined low voltage (LV) and medium voltage (MV) residential grid impact for slow and fast electric vehicle (EV) charging, for an increasing local penetration rate and for different residential slow charging strategies. A realistic case study for a Flemish urban distribution grid is used, for which three residential slow charging strategies are modeled: uncoordinated charging, residential off-peak charging, and EV-based peak shaving. For each slow charging strategy, the EV hosting capacity is determined, with and without the possibility of fast charging, while keeping the grid within its operating limits. The results show that the distribution grid impact is much less sensitive to the presence of fast charging compared to the slow charging strategy. EV-based peak shaving results in the lowest grid impact, allowing for the highest EV hosting capacity. Residential off-peak charging has the highest grid impact, due the load synchronization effect that occurs, resulting in the lowest EV hosting capacity. Therefore, the EV users should be incentivized to charge their EVs in a more grid-friendly manner when the local EV penetration rate becomes significant, as this increases the EV hosting capacity much more than the presence of fast charging decreases it.
Valero, D.; Olivella, P.; R. Villafafila-Robles; Cestau, S. IEEE International Electric Vehicle Conference p. 1-6 DOI: 10.1109/IEVC.2014.7056161 Data de presentació: 2014-12-19 Presentació treball a congrés